Desmoplakin II expression is not restricted to stratified epithelia.
Desmoplakin II expression is not restricted to stratified epithelia.
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DOI：
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发表时间：
1990-10
影响因子：
4
通讯作者：
B. Angst;L. A. Nilles;K. J. Green
中科院分区：
文献类型：
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作者：
B. Angst;L. A. Nilles;K. J. Green
桥粒是上皮组织、心脏组织和蛛网膜组织中与中间丝相关的主要细胞间连接。桥粒蛋白I和II （DPI和II）是高度相关的蛋白，位于桥粒斑块的最内层，是连接中间丝（IF）和桥粒复合物的候选蛋白。虽然研究人员同意DPI存在于所有上皮中，但他们对DPII的分布存在分歧。一些报道称DPII仅限于分层组织，并进一步表明DPII的表达可能与分层有关。我们比较了单纯上皮、移行上皮和分层上皮细胞系中DPI和II在mRNA和蛋白水平上的表达。Northern blot分析显示，DPI和II mRNA存在于所有细胞系以及简单和分层上皮组织中。而心肌组织中未检测到DPII mRNA。免疫印迹和免疫沉淀表明，在全细胞蛋白水平上，DPI和II存在于所有细胞系中，并与细胞骨架部分相关。用免疫荧光染色将生化结果与DPI和II的定位联系起来。虽然大多数细胞系表现出典型的细胞间和细胞质DP染色，但T24细胞主要表现为弥漫性和多点细胞质染色。此外，我们还研究了钙诱导的人咽部细胞系FaDu细胞接触形成和分层后，DPI和II的表达是否发生变化。在钙转换后的5天内，未观察到mRNA或全细胞蛋白水平的显著变化。然而，免疫印迹显示，在桥粒形成过程中，不溶性蛋白池中的DPI和II水平显著增加。这些观察结果表明，在钙开关诱导桥粒组装后，可溶性DPI/II可能被募集到一个不溶池中，这与早期关于MDCK细胞的报道一致。总之，我们的结果表明，DPII的表达与分层或分化没有严格的联系；然而，心肌中DPII mRNA的明显缺失表明它可能不是所有桥粒的组成部分。
Desmosomes are major intercellular junctions found in association with intermediate filaments in epithelial, cardiac and arachnoidal tissue. Desmoplakins I and II (DPI and II) are highly related proteins localized in the innermost part of the desmosomal plaque and are candidates for linking intermediate filaments (IF) to the desmosomal complex. While investigators agree that DPI is present in all epithelia, they disagree on the distribution of DPII. Some have reported DPII to be restricted to stratified tissue and have furthermore suggested that the expression of DPII may be linked to stratification. We have compared the expression of DPI and II at the mRNA and protein levels in cell lines derived from simple, transitional and stratified epithelia. Northern blot analysis revealed DPI and II mRNA to be present in all cell lines as well as simple and stratified epithelial tissues. However, DPII mRNA could not be detected in cardiac muscle tissue. Immunoblotting and immunoprecipitation demonstrated the presence of DPI and II in all cell lines at the whole-cell protein level as well as in association with cytoskeletal fractions. Immunofluorescence staining was used to correlate the biochemical findings with the localization of DPI and II. While most cell lines exhibited typical intercellular and in many cases cytoplasmic DP staining, T24 cells exhibited predominantly diffuse and dotty cytoplasmic staining. In addition, we investigated whether changes in DPI and II expression occurred following calcium-induced cell contact formation and stratification in the human pharyngeal cell line, FaDu. No significant changes in mRNA or whole-cell protein levels were observed during a period of 5 days following the calcium switch. However, immunoblotting revealed a significant increase in DPI and II levels in the insoluble protein pool during desmosome formation. These observations indicated a possible recruitment of soluble DPI/II into an insoluble pool after induction of desmosome assembly by the calcium switch, consistent with earlier reports for MDCK cells. In summary, our results suggest that the expression of DPII is not strictly linked to stratification or differentiation; however, the apparent absence of DPII mRNA from cardiac muscle suggests it may not be a constituent of all desmosomes.